(1) Field of the Invention
The invention relates to non-volatile type of electronic memories associated with a microcontroller so that the microcontroller can carry out operations in accordance with instructions and data contained in the memories. In particular, it relates to a device and a method of providing protection for one or several parts or sectors or areas of these memories against unauthorized reading.
(2) Description of Related Art
It is known how to globally protect a memory against writing and/or reading by preventing access to the memory in write and/or in read as soon as a protection bit has been put into a specific state or a fuse has been “burned”.
Although the memory is protected in read, it must be accessible in read if a read request is made as a result of a program instruction. Consequently, a memory protected in read must also be protected in write to prevent a fraudor from being able to write a program of instructions into the memory accessible in write, in order to read the read protected memory.
Therefore, one purpose of this invention is to make a device capable of protecting all or part of a non-volatile type of electronic memory against unauthorized reading, in other words reading that does not correspond to execution of an instruction code.